Reset IC with 2.925 V threshold, open-drain, and 6 second reset timer

David Sandler

Intellectual 1910 points

Other Parts Discussed in Thread: TPS3420, TPS3897

Hi,

I'm looking for a reset IC with a reset threshold at 2.925V, open drain config. I saw the TPS3106K33,TPS3110K33, and TPS3813K33. The reset IC I am trying to replace has a minimum setup period for the reset input to be held low. There is currently a 6 second period require before a reset output is triggered. I need a supervisor IC with delayed reset output capability once a reset input (button press) is detected. We are using this to hard-reset our device after a button is pressed for 6 seconds to be more specific. I brought up the watchdog timer but I was told this cannot be used to solve this 6 second delay. Any suggestions?

Thanks,

David

over 10 years ago

0 David Hopkins over 10 years ago

TI__Expert 8905 points

Hi David,

We actually have push-button controllers that seems to be perfectly suited for what you are describing as your application, with the exception of the threshold of 2.925V. Have you looked at the TPS3420?

Regards,
David

0 David Sandler over 10 years ago in reply to David Hopkins

TI__Intellectual 1910 points

the TPS3420 would be perfect other than the lack of the threshold voltage. Do you have any suggestions to duplicating that part of the functionality?

0 David Hopkins over 10 years ago in reply to David Sandler

TI__Expert 8905 points

The only way I can think of is to drive the input pin with another supervisor. Most of our supervisors are designed to be as fast as possible to assert reset as that is the typical customer requirement, and than the set set is from when RST/ is first asserted until it is released.

0 David Sandler over 10 years ago in reply to David Hopkins

TI__Intellectual 1910 points

What I really need is a reset IC/supervisory circuit that has a setup time so it doesn't assert before the system can power up properly.

Thanks,

David

0 David Hopkins over 10 years ago in reply to David Sandler

TI__Expert 8905 points

Hi David,

Sorry took a little bit on this one - we do have an application solution for this one:

Regards,

David

0 David Hopkins over 10 years ago in reply to David Hopkins

TI__Expert 8905 points

Weird - it didn't post the schematic. Anyway, the basic schematic is below (2nd attempt) - the goal is to give you an adjustable setup time by changing the capacitor on the topmost TPS3897. The rail sequencing is a bit tricky but if you want more detail just ask (may take a bit due to the upcoming holiday).

Regards,

David

Power management

Power management forum

Reset IC with 2.925 V threshold, open-drain, and 6 second reset timer